Rocket Validator integrates the W3C Validator HTML checker into an automated web crawler.
Related W3C validator issues
In order to define the charset encoding of an HTML document, both of these options are valid, but only one of them must appear in the document:
<!-- This is the preferred way --> <meta charset="UTF-8"> <!-- This is the older way, also valid --> <meta http-equiv="content-type" content="text/html; charset=UTF-8">
The only value admitted for the attribute content in a <meta http-equiv="X-UA-Compatible"> is currently IE=edge. You’re probably seeing this issue because the page being validated includes the following meta tag:
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
As the Google Chrome Frame plugin was discontinued on February 25, 2014, this is longer supported so you should change that meta tag to:
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
According to this article in Wikipedia:
Google Chrome Frame was a plug-in designed for Internet Explorer based on the open-source Chromium project, first announced on September 22, 2009. It went stable in September 2010, on the first birthday of the project. It was discontinued on February 25, 2014 and is no longer supported.
A <meta> element using the http-equiv attribute has been found in an unexpected place of the document. It should appear inside the <head> section, like in this example:
<!DOCTYPE html> <html lang=""> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Test</title> </head> <body> <p>Content of the page</p> </body> </html>
The http-equiv attribute is used in web pages to simulate an HTTP response header. While HTTP response headers can be set from the server, not everyone has access to the server configuration, so an alternative is using <meta http-equiv> to define settings that would otherwise require setting an HTTP response header.
The most popular use of http-equiv are defining the content-type of the document as in the example above, although in HTML5 it’s preferred to use this instead:
Another popular use of the http-equiv is setting an automatic reload of the web page, for example this will have the browser reload the page every 60 seconds:
<meta http-equiv="refresh" content="60">
However, refreshing a page automatically is a bad practice regarding accessibility, as users do not expect a page to do that, and doing so will move focus back to the top of the page, which may create a frustrating or confusing experience.
Other values that can be used with the http-equiv attribute include:
According to W3C, http-equiv value content-script-type attribute is unknown for HTML5 meta markup.
According to W3C, http-equiv value content-style-type attribute is unknown for HTML5 meta markup.
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